1. Field of the Invention
The present invention relates to communication systems and more particularly to wireless communication systems.
2. Description of the Related Art
Communication systems and in particular, wireless communication system are designed to meet the varying demands of their subscribers. Service providers, which are entities that own, operate and properly maintain the communication system, are constantly seeking ways to improve the overall performance of a communication system without incurring substantial cost increases in the operation of such communication systems. In particular, as wireless communication systems become more and more popular, service providers have to provide communication systems that allow subscribers to convey (i.e., transmit and/or receive) relatively larger amounts of information per unit time. The amount of information conveyed per unit time is the information rate. The total amount of information that can be conveyed over a system is usually referred to as a system's capacity. The amount of information that is successfully conveyed (i.e., information transmitted and received without errors) over a communication system is usually referred to as system throughput. Subscribers of a communication system with a certain system capacity are limited in the amount of information they can convey at any instant of time. Depending on the conditions of the communication channels through which the subscribers convey information, the subscriber throughput and/or capacity will not remain fixed. Therefore, there may be times when a subscriber desires to convey information at a certain information rate with a certain throughput, but will not be able to do so because of adverse channel conditions. In particular, the communication system may not be able to accommodate a subscriber desiring relatively higher information rates.
To address the problem of a subscriber's inability to convey information at a desired information rate, subscribers use equipment (e.g., cell phones or mobiles) that have multiple antennas instead of only one antenna. The use of additional antennas in a subscriber's equipment gives the subscriber the ability to convey information at relatively higher rates. However, the increased capacity of the subscriber's equipment through the use of additional antennas will still be limited by the system's capacity at any instant of time. For example, a subscriber equipment having multiple antennas may have the capability and desire to convey information at a certain rate, but will be limited to a lesser rate by the system at a particular instant of time. In sum, it is the system's capacity—not the capacity of a subscriber's equipment—which ultimately governs the rate at which a subscriber conveys information. Furthermore, the use of multiple antennas in subscriber equipment complicates the design of such equipment, complicates how the subscriber equipment communicates with the communication system and increases the cost of the subscriber equipment.
System capacity and system throughput are two examples of system requirements that service providers want to manipulate so as to operate their communication systems in an efficient manner. Other examples of system requirements are the power allocation to the communication system and system delay experienced by the subscribers of the communication system. The power allocation refers to the amount of power available and the proportional amount of power allocated to each communication channel being used by one or more subscribers. System delay refers to the amount of latency experienced by subscriber signals as a result of such signals being processed by system equipment owned, operated and maintained by the service provider. System providers want to provide relatively large system capacity and throughput to their subscribers with the amount of total power available to the system while reducing system delay as much as possible. Many times these system requirements conflict with each other and make it difficult to achieve efficient operation of the communication system. Service providers often resort to buying additional equipment to satisfy one or more of the system requirements. What is therefore needed is a method and system where one or more system requirements can be achieved without the service provider incurring the cost of additional equipment.